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_МЕЖДУНАРОДНЫЙ НАУЧНЫЙ ЖУРНАЛ «ИННОВАЦИОННАЯ НАУКА» №9/2016 ISSN 2410-6070_
УДК 69.04
M.V. Kosheleva
Second-year Master's degree student, Institute of Civil Engineering and Architecture, Northern (Arctic) Federal University named after M.V. Lomonosov Scientific adviser: [A.V. Veshnyakov] PhD, Associate Professor Northern (Arctic) Federal University named after M.V. Lomonosov
Scientific adviser: O.B. Bessert PhD, Associate Professor Northern (Arctic) Federal University named after M.V. Lomonosov
Arkhangelsk, Russian Federation
COMPARISON OF DESIGN STANDARDS OF CONCRETE AND REINFORCED CONCRETE
STRUCTURES: CR&R 2.03.01-84*, CR&R 52-101-2003 (CP 52-101-2003) AND CP 63.13330.2012
Annotation
The design standards of concrete and reinforced concrete structures have changed for almost three decades. The authors analyze the changes in the definition of the ultimate bending moment and the moment of cracks formation.
Key words
Ultimate bending moment, moment of cracks formation, percentage of reinforcement, concrete structure, reinforced concrete structure, CR&R 2.03.01-84*, CR&R 52-101-2003, CP 52-101-2003, CP 63.13330.2012
Before the introduction of the "Technical regulation on safety of buildings and constructions", the design of concrete and reinforced concrete structures was carried out according to CR&R 2.03.01-84* "Concrete and reinforced concrete structures" [1].
Since July 1, 2010 the Federal Law (FL), dated December 30, 2009, No. 384-FL "Technical regulation on safety of buildings and constructions" [2] is regulating the safety of buildings and constructions on the territory of the Russian Federation.
In accordance with Part 1 of Article 6 and Part 3 of Article 42 of the FL [2] "List of national standards and codes of practice (parts of such standards and codes of practice), with the obligatory result of application in accordance with the requirements of the FL "Technical regulation on safety of buildings and constructions", approved by the Directive of the RF Government No. 1047-r, dated June 21, 2010 [3], was developed. In accordance with this List [3] the requirements of CR&R 52-01-2003 "Concrete and reinforced concrete structures. Principal rules" [4] with the further document CP 52-101-2003 "Concrete and reinforced concrete structures without prestressing" [5] were obligatory for application from July 1, 2010 to June 31, 2015.
The new "List of national standards and codes of practice (parts of such standards and codes of practice), with the obligatory result of application in accordance with the requirements of the FL "Technical regulation on safety of buildings and constructions" was approved by the Resolution of the RF Government No. 1521, dated December 26, 2014 [6]. In concordance with paragraph 6 of the Resolution [6] the Directive [3] is repealed from July 1, 2015. According to the List [6], the requirements of CP 63.13330.2012 "Concrete and reinforced concrete structures. Principal rules" are obligatory for application from July 1, 2015.
The purpose of this research is to analyze the changes in the calculations on the strength of cross-sections normal to the longitudinal axis of the bent elements, as well as calculations of the moment of formation of cracks in normal sections. As an example rectangular section of beam with the sizes 200^450 (h) mm was considered. Herewith the working height of section is h0 = 420 mm at the diameter of reinforcing bar ds < 20 mm, h0 = 405 mm at ds = 22 - 28 mm, h0 = 390 mm at ds = 32 - 40 mm. Reinforcement of the beam is provided by welded frame with
_МЕЖДУНАРОДНЫЙ НАУЧНЫЙ ЖУРНАЛ «ИННОВАЦИОННАЯ НАУКА» №9/2016 ISSN 2410-6070_
the class of single reinforcement - A400 (A-III); concrete strength class is B20. The properties of the materials according to the design standards are summarized in Table 1.
Table 1
Strength and deformation properties of the materials
Design code Concrete B20 Fittings А400 (A-III)
Properties of concrete, MPa £ Diameter, mm Properties of fittings, MPa
Rbt,ser Rb Rbt e £ £ й Eb-103 Rs Es-105
CR&R 2.03.01-84* 1.40 11.5 0.90 10.35 0.81 27.0 0.9 6-8 355 2.0
1040 365
CP 52-101-2003 1.35 11.5 0.90 10.35 0.81 27.5 0.9 6-40 355 2.0
CP 63.13330.2012 1.35 11.5 0.90 10.35 0.81 27.5 0.9 6-40 350 2.0
The graphs of dependences of the ultimate bending moment Mu and the moment of formation of cracks Mcrc accordingly from percentage of reinforcement, which is calculated for the nominal diameter of rods (from 06 to 040), are presented in Figures 1 and 2.
VI „, kH-m
160 140 120 100 80 60 40 20 0
133 .28 13 7.99 1' 143.
114.1 1 1 1 s 13C 3 À ï // 9 1.0912 )-< 123 3.09 0
93." 91 ( 6 À Ъ/f1 10.66 12 2.8012 2.80 122
69.É 83. 81. >9 j 58 63^ ^90 64
56.^ 55.( 68.( f J J пЖ 65
jJ 44 43. 00 j 1 i л? 16 j 04 ¿у ty 0 / 31 ID
0 71 i 14 ¡10 14 23 .75 22 75 ^ .27 66^' i^b 1 ¡^42 71 47
У. / L о 5.67 5 о-- .67^ rf^ Г 22 55 35
09
80
0 0.07 0.12 0. —•—Mu C.R&R 2.0
19 0.27 0.37 0.48 0.61 0.75 0.94 1.21 1.52 2.06 2.61 3.22 3.01-84* —»-MuCP 52-101-2003 —"-Mu CP 63.13330.2012 Ms) %
Figure 1 - Graphs of dependences Mu = f(ps)
МЕЖДУНАРОДНЫЙ НАУЧНЫЙ ЖУРНАЛ «ИННОВАЦИОННАЯ НАУКА» №9/2016 ISSN 2410-6070
0 0.07 0.12 0.19 0.27 0.37 0.48 0.61 0.75 0.94 1.21 1.52 2.06 2.61 3.22 -Mere CR&R 2.03.01-84* -♦-Mere CP 52-101-2003 -»-Mere CP 63.13330.2012 Ms) % Figure 2 - Graphs of dependences Mcrc = f(ps)
As you can seen in Figure 1, the value of ultimate bending moment, perceived by cross-section of beam at the same class of concrete and at identical reinforcing, decreases with the change of design standards (CR&R 2.03.01-84*, CP 52-101-2003, CP 63.13330.2012).
This is caused by the change of strength properties of fittings, established by corresponding standards: namely, the reduction of the design resistance to tension of longitudinal reinforcement for limiting states of the first group by increasing the coefficients of reliability for fittings Ys. The decrease of the ultimate bending moment of a concrete element is caused by the presence of the elastic moment of resistance, which in 1.7 times is less than the elastic-plastic moment of resistance, used in the calculation according to the CR&R [1].
The minimum percentage of reinforcement of reinforced concrete cross-section at the transition from CR&R to CP was increased from 0.05% to 0.1%. When the relative height of the compressed zone of the concrete exceeds its boundary value (£ > ¿R), the increase in cross-section area of tensile reinforcement stops to raise the value of the ultimate bending moment, as it was in the calculation according to CR&R.
It should be noted that with the exceeding of the maximum percentage of reinforcement, the value of the ultimate bending moment, calculated in accordance with CP 63.13330.2012, exceeds the value of the ultimate bending moment, calculated according to CP 52-101-2003. This is related to the increase in the boundary relative height of the compressed zone of the concrete in CP 63.13330.2012 compared to CP 52-101-2003, which is inversely proportional to the design resistance to tension of longitudinal reinforcement.
According to Figure 2, the highest value of the moment of formation of cracks is obtained at calculation according to CR&R 2.03.01-84, the least - according to CP 52-101-2003 and intermediate - CP 63.13330.2012. This is mainly caused by the fact that the calculations according to CR&R 2.03.01-84* and CP 63.13330.2012 unlike CP 52-101-2003 (where the calculation was carried out predominantly in the elastic stage), plastic deformations of the concrete are taken into account by multiplying the moment of resistance of reduced section by a coefficient of 1.75 and 1.3 respectively. At drawing up of CP 63.13330.2012 in calculation of the formation of cracks the authors of standards tried to return to the previous accounting of plastic deformation of concrete by introducing the coefficient, which is slightly lower than in CR&R, that nevertheless has allowed to raise the moment of the formation of the cracks as compared with the calculation according to CP 52-101-2003. In addition, the design resistance to tension of concrete for limiting states of the second group has decreased, and the modulus of elasticity of concrete has increased in CP in comparison with CR&R.
In general, with the development of the design standards, most of the changes has led to the increase of reinforcement consumption, which in turn will cause a rise in price of construction, because the minimum consumption of reinforcement was made in calculations according to CR&R 2.03.01-84*. CP 63.13330.2012 is the most uneconomic design standard according to reinforcement consumption while the ultimate bending moment was
_МЕЖДУНАРОДНЫЙ НАУЧНЫЙ ЖУРНАЛ «ИННОВАЦИОННАЯ НАУКА» №9/2016 ISSN 2410-6070_
determined.
References:
1. CR&R 2.03.01-84*. Concrete and reinforced concrete structures. - Introduced 1986-01-01 - M.: Central institute of standard design of State Committee of the USSR Council of Ministers for Construction, 1989. - 80 p.
2. Federal Law dated December 30, 2009, No. 384-FL "Technical regulation on safety of buildings and constructions" Federal Law: adopted by State Duma on December 23, 2009; approved by Federation Council December 25, 2009 - М.
3. List of national standards and codes of practice (parts of such standards and codes of practice), with the obligatory result of application in accordance with the requirements of the FL "Technical regulation on safety of buildings and constructions": approved by Directive of the RF Government No. 1047-r, dated June 21, 2010.
4. CR&R 52-01-2003. Concrete and reinforced concrete structures. Principal rules. - Introduced 2004-03-01 - M.: Federal State Unitary Enterprise "Center of design products of mass application", 2004. - 31 p.
5. CP 52-101-2003. Concrete and reinforced concrete structures without prestressing. - Introduced 2004-03-01 -M.: Federal State Unitary Enterprise "Center of design products of mass application", 2004. - 59 p.
6. List of national standards and codes of practice (parts of such standards and codes of practice), with the obligatory result of application in accordance with the requirements of the FL "Technical regulation on safety of buildings and constructions": approved by Resolution of the RF Government No. 1521, dated December 26, 2014.
7. CP 63.13330.2012. Concrete and reinforced concrete structures. Principal rules. - Introduced 2004-03-01 - M.: Ministry of Construction, Housing and Utilities of the RF, 2015. - 168 p.
© Kosheleva M.V., [Veshnyakov A.V.], Bessert O.B., 2016
УДК 004
А.С. Митрофанов
к.т.н., руководитель группы мониторинга программы «Развитие» Союз ИТЦ «России», г. Москва, РФ
e -mail:_a.s .mitrofanov@ruitc.ru А.Ф.Власов Эксперт Союз ИТЦ «России» г. Москва, РФ М.А.Махиборода к.ф-м.н. Генеральный директор ООО «Сенсор Микрон», г. Зеленоград e-mail: m.makhiboroda@gmail.ru Н.А.Дюжев к.ф-м.н. технический директор ООО «Сенсор Микрон», г. Зеленоград
ИСПОЛЬЗОВАНИЕ МАЛЫМ ПРЕДПРИЯТИЕМ ФИНАНСИРОВАНИЯ ПО ПРОГРАММЕ «РАЗВИТИЕ» ФОНДА СОДЕЙСТВИЯ ИННОВАЦИЯМ ДЛЯ РАЗРАБОТКИ И ВЫВОДА НА РЫНОК СЕМЕЙСТВА МЭМС-ДАТЧИКОВ НА ОСНОВЕ ТЕРМОРЕЗИСТОРОВ
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